x86: Add Intel Edison board files

x86: Add Intel Edison board files

Add Intel Edison board which is using U-Boot.

The patch is based on work done by the following people (in alphabetical
order):
	Aiden Park <aiden.park@intel.com>
	Dukjoon Jeon <dukjoon.jeon@intel.com>
	eric.park <eric.park@intel.com>
	Fabien Chereau <fabien.chereau@intel.com>
	Felipe Balbi <felipe.balbi@linux.intel.com>
	Scott D Phillips <scott.d.phillips@intel.com>
	Sebastien Colleur <sebastienx.colleur@intel.com>
	Steve Sakoman <steve.sakoman@intel.com>
	Vincent Tinelli <vincent.tinelli@intel.com>

In case we're building for Intel Edison, we must have 4096 bytes of
zeroes in the beginning on u-boot.bin. This is done in
board/intel/edison/config.mk.

First run sets hardware_id environment variable which is read from
System Controller Unit (SCU).

Serial number (serial# environment variable) is generated based on eMMC
CID.

MAC address on USB network interface is unique to the board but kept the
same all over the time.

Set mac address from U-Boot using following scheme:
	OUI = 02:00:86
	next 3 bytes of MAC address set from eMMC serial number

This allows to have a unique mac address across reboot and flashing.

Signed-off-by: Vincent Tinelli <vincent.tinelli@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
[bmeng: Add MAINTAINERS file for Intel Edison board]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>